Mkay, that's because the game is built with an old version of nw.js, which kind of blows and causes a lot of problems. The older version is unable to parse the font config file, and throws a fit like an anime teen who's encountered a minor inconvenience in their daily life. Try this from the game directory (where nw is):
mkdir fonts
echo -e "<fontconfig>\n\t<dir>/usr/share/fonts</dir>\n\t<cachedir>fonts</cachedir>\n</fontconfig>" > fonts/fonts.conf
then start the game with
FONTCONFIG_PATH=fonts ./nw
What that basically does is make an empty font config file with nothing for the older parser to panic about. Give it a go and see if there are any launch-breaking errors left.
If you prefer to get away from the terminal, shove the above launch command in a shell script and make that executable. Then you can just run it from whatever file manager you use:
echo -e "#!/bin/sh\nFONTCONFIG_PATH=fonts ./nw" > start.sh
chmod +x start.sh